theory11 — Magic Tricks & the World's Finest Playing Cards
First of all, what do you have? Second, what have you studied?
Since you're a card guy, I'll mention the section on mental discoveries in Expert Card Technique, and there are a few tricks in Royal Road that lend themselves to a mentalist twist. Try your hand at a few of those and see what reactions you get. I'll also recommend you get Mark Wilson's Complete Course in Magic and/or the Tarbell Course. Both have great sections on mentalism work. After that, there's always Anemanns Practical Mental Magic or Corindia's 13 Steps to Mentalism.
As far as DVD's go the This is Mentalism Series is great.
Before you get too far into it, here's a quote from David Berglas at the 2012 EMC conference. Don't take this as me saying don't try mentalism, do try it, but keep this in mind. This quote is in response to the question, what advice do you have for a beginner studying and trying to learn both magic and mentalism?
"Well they won't like it. As you know I'm extremely passionate about magic and I don't think you should be a mentalist or even put in a mentalist routine unless you have that kind of personality… It depends very much on believability… Stick to magic which there are so many different phases. As far as mentalists are concerned, once you've got the confidence to speak to people and make yourself believable, then start trying some mentalist things."